Detailed genetic analysis of feeding behaviour in Romane lambs and links with residual feed intake

Breeding strategies based on feed efficiency are now implemented in most animal species using residual feed intake (RFI) criteria. Although relevant, the correlated responses of feeding behaviour traits resulting from such selection on RFI are poorly documented. We report the estimated feeding behaviour at three time levels (visit, meal and day) and genetic parameters between the feeding behaviour traits and their links with RFI and its components. Feed intake, feeding duration at three time levels (per visit, meal and day), feeding rate, number of visits and time‐between‐visits were estimated for 951 Romane lambs fed via automatic concentrate feeders. Heritability estimates of feeding behaviour traits ranged from 0.19 to 0.54 with higher estimates for the day level than the visit level. Daily feed intake was not genetically linked to feed intake at the visit level, whereas feeding duration between visit and day levels was moderately correlated (R_g = +0.41 ± 0.12). RFI was not significantly correlated with feeding rate, but was positively linked to feed intake and feeding duration at the day level (+0.73 ± 0.09 and +0.41 ± 0.13, respectively) and negatively at the visit level (?0.33 ± 0.14 and ?0.22 ± 0.17, respectively). Selecting animals with lower RFI values might modify their feeding behaviour by increasing feed intake and feeding duration at the visit level but decrease the number of visits per day (+0.51 ± 0.14).     

Estimates of genetic parameters for feed intake, feeding behavior, and daily gain in composite ram lambs

Our objective was to estimate genetic parameters for feed intake, feeding behavior, and ADG in composite ram lambs ((1/2) Columbia, (1/4) Hampshire, (1/4) Suffolk). Data were collected from 1986 to 1997 on 1,239 ram lambs from approximately 11 to 17 wk of age at the U.S. Meat Animal Research Center near Clay Center, NE. Feeding equipment consisted of an elevated pen with an entrance chute that permitted access to the feeder by only one ram lamb at a time, with disappearance of feed measured by an electronic weighing system. Ram lambs were grouped 11 per pen from 1986 to 1989, and nine per pen from 1990 to 1997. Data were edited to exclude invalid feeding events, and approximately 80% of the data remained after edits were applied. Traits analyzed were daily feed intake (DFI), event feed intake (EFI), residual feed intake (RFI), daily feeding time (DFT), event feeding time (EFT), number of daily feeding events (DFE), and ADG. Feed intake traits of DFI and EFI had estimated heritabilities of 0.25 and 0.33, respectively, whereas estimated heritability of RFI was 0.11. Heritability estimates for feeding behavior traits, including DFT, EFT, and DFE, ranged from 0.29 to 0.36. Average daily gain had an estimated heritability of 0.26. Genetic correlations were positive between all pairs of traits, except for RFI and ADG, and that estimate was essentially zero. Phenotypic correlations were generally similar to genetic correlations. Genetic correlations were large (0.80) between DFI and ADG, intermediate between DFI and RFI (0.61) and between DFT and DFE (0.55), and low (0.17 to 0.31) for the other pairs of traits, with the exception of RFI and ADG (-0.03). Genetic correlations between behavioral traits were greater than correlations between behavioral traits and measures of feed intake or ADG; however, selection for ADG and/or feed intake would be expected to cause some changes in feeding behavior.     

Effects of number of lambs suckled and supplemental protein source on lactating ewe performance

Effects of number of lambs suckled and supplemental protein source on ewe performance were determined. Lactation performance of ewes nursing twin or triplet lambs was compared in Exp. 1 and 2. In Exp. 1, ewes giving birth to and nursing triplets produced 21% (P less than .05) more milk/unit metabolic body weight, were 10% more efficient in the conversion of feed to milk and produced 26% (P less than .05) more kg of lamb/ewe on d 42 of lactation than did ewes giving birth to and nursing twins. In Exp. 2, lactation performance of ewes giving birth to triplets and rearing only two lambs was compared with performance of ewes giving birth to triplets and rearing three lambs. Ewes rearing three lambs produced 28% (P less than .08) more milk and were 26% (P less than .05) more efficient in converting feed to milk than were those rearing two lambs. This suggests that direct nursing stimulation of the mammary gland is responsible for the improvement in milk production observed when ewes nurse additional lambs. The efficacy of slowly degradable protein sources for improved lactation was studied in Exp. 3 and 4. When blood meal was fed to twin-rearing ewes at 3.30% of the diet (25% of total dietary protein), milk production was greater (3,176 vs. 2,506 g/d, P less than .05) and efficiency of milk production was greater (1.05 vs .79 g milk/g feed, P less than .05) than when ewes were fed supplemental soybean meal. Ewes in this experiment fed supplemental meat and bone meal also tended to produce more milk than those fed soybean meal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of maternal selenium supply and plane of nutrition during gestation on passive transfer of immunity and health in neonatal lambs

To investigate the influence of maternal Se supply and plane of nutrition on lamb morbidity, mortality, and passive transfer of IgG, pregnant ewe lambs were used in 2 experiments with 2 × 3 factorial treatment arrangements. Supplementation of Se began at breeding and was either adequate Se (ASe, 9.5 μg/kg of BW) or high Se (HSe, 81.8 μg/kg of BW) in Exp. 1 or ASe (11.5 μg/kg of BW) or HSe (77.0 μg/kg of BW) in Exp. 2. On d 50 or 40 of gestation for Exp. 1 or 2, respectively, ewes were assigned randomly to 1 of 3 nutritional planes: 60% (RES), 100% (control, CON), or 140% (HI) of NRC requirements. This resulted in the following treatments: ASe-RES, ASe-CON, ASe-HI, HSe-RES, HSe-CON, and HSe-HI. Upon parturition, lambs were separated from their dams and serum samples obtained. Lambs were fed artificial colostrum for the first 20 h and then placed on milk replacer and grain pellets until completion of the study (Exp. 1, 57 d; Exp. 2, 21 d). Twenty-four hours after parturition, lamb serum samples were collected for IgG analysis. All lambs were reared similarly and morbidity and mortality assessed. Main effects were considered significant when P ≤ 0.05. In Exp. 1, there was a Se × plane of nutrition interaction (P ≤ 0.01) for lamb morbidity from birth to weaning and for 24-h IgG concentration. Lambs from ASe-RES and HSe-HI ewes were treated more frequently (P < 0.01) for respiratory and gastrointestinal disease, and lambs from HSe-HI ewes had the smallest (P < 0.01) 24-h serum IgG concentration. In Exp. 1, lambs from HI ewes also had the greatest (P < 0.01) mortality rates from birth to weaning compared with lambs from CON and RES ewes. In Exp. 2, there was an effect (P < 0.01) of maternal plane of nutrition with lambs from RES ewes having increased 24-h IgG compared with lambs from CON and HI ewes. There was no effect of maternal Se supplementation on lamb 24-h IgG in Exp. 2; however, there was a Se × plane of nutrition interaction (P < 0.01) for morbidity. From birth to 21 d of age, lambs from ASe-CON ewes had fewer (P < 0.01) treatment days compared with lambs from any of the other treatment groups. There also tended (P = 0.08) to be an effect of maternal Se supplementation on lamb mortality with increased mortality observed in lambs from HSe ewes. Results from the studies show a restricted maternal plane of nutrition can increase lamb serum IgG concentration. Selenium results were not consistent between the 2 experiments and may be due to differences in maternal Se.     

The effect of dietary yeast and protected methionine on performance and trace minerals status of growing Awassi lambs

Eighteen growing Awassi lambs were used in this study to determine the effect of supplementing two levels of yeast and methionine (cyc-methionine) on the trace elements bioavailability, growth rate, and general performance. The lambs were divided to three groups. The dietary treatments were the control diet (C), control diet plus 2 g cyc-methionine/lamb/day (T₁) and control diet plus 4 g cyc-methionine/lamb/day (T₂).

Lambs fed 2 g/day of cyc-methionine (T₁) showed a significantly higher (P < 0.05) copper, zinc, and cobalt concentrations in liver and meat tissues, but not the same trend in kidney. No significant (P > 0.05) effect of time and time × treatment interaction on copper, zinc, cobalt, and manganese concentrations in blood serum, but cobalt and manganese concentration showed significant (P < 0.05) change by time. Moreover, a significantly (P < 0.05) higher total body gain, average daily gain, dressing percentage, and lower feed conversion were detected in lambs from T₁ compared with the control and T₂ groups.

Feeding 2 g of cyc-methionine to growing lambs increased the net profit by $6.017/lamb and only $3.52/lamb fed 4 g cyc-methionine/day when compared with the control group.

In conclusion, feeding growing Awassi lambs yeast and methionine in a form of cyc-methionine, with a low level of 2 g/day, improve the bioavailability of copper, zinc, and cobalt by growing lambs and their growth performance.     

Growth, haematology, blood constituents and immunological status of lambs fed graded levels of animal feed grade damaged wheat as substitute of maize

The aim of this study was to explore possibilities of utilization of animal feed grade damaged wheat (ADW) in lamb feeding, and assess the effect of ADW and its aflatoxin on intake, growth, haematology, blood biochemical constituents and immunological status. The ADW is a slightly mouldy feed resource, which is not suitable for human consumption. The experimental ADW contained dry matter (DM) 964, organic matter 974, crude protein 153, cellulose 205 and lignin 24, and starch 732 g/kg DM. ADW also contained aflatoxin B1 50 microg/kg due to mould infestation. Thirty-five weaner lambs (90 +/- 15 days of age and 16.1 +/- 0.82 kg body weight) in a randomized design were fed for 91 days on one of four composite feed mixtures (roughage to concentrate ratio of 25:75) containing 0, 118, 235, 353 or 470 g/kg ADW, which replaced equal amounts of maize and at these inclusion levels ADW replaced 0%, 25%, 50%, 75% and 100% maize in lamb diets respectively. Dry matter intake (DMI) was similar in different level of ADW fed lambs but ADW inclusion linearly (p = 0.016) reduced DMI. Average daily gain (g/day) was higher (p = 0.038) in lambs fed 353 g ADW diet. Haematological attributes viz. WBC, haemoglobin (Hb) and mean corpuscular volume did not affect by ADW feeding whereas it increased haematocrit, mean cell Hb and decreased neutrophil, RBC counts and mean cell Hb concentration. Blood glucose and urea-N increased whereas albumin and protein level reduced by ADW feeding. ADW feeding of lambs did not affect serum IgG level. The activities of serum aspartate aminotransferase, alkaline phosphates and acid phosphates were not affected, whereas alanine aminotransferase increased linearly (p = 0.001) with increasing levels of ADW. It is concluded that ADW containing aflatoxin B1 50 microg/kg DM can safely be incorporated in growing lamb feeding up to 353 g/kg diet without affecting growth and cellular immunity, however ADW may induce a transient alteration of hepatic enzymatic activities. Further aflatoxin content of the diet should be kept within permissible limits of respective country.     

Role of magnesium in the aetiology of ovine urolithiasis in fattening store lambs and intensively fattened lambs

High dietary levels of magnesium (greater than 2 g/kg drymatter [DM]) have been implicated as the main causal factor of urinary calculi in concentrate-fed lambs. Experiments were performed to try to reproduce this effect of high magnesium (from added calcined magnesite) on the incidence of urolithiasis in lambs. In the first, store lambs were given diets containing magnesium in the following concentrations: A,2.9; B,8.6 g/km DM. Twenty-four blackface lambs were each allocated to A and B and the control group of 160 lambs was fed a combined dried grass/sugar beet pulp pellet and hay ad libitum (diet C). The animals were housed and fed ad libitum until they were killed at an average liveweight of 35 kg. No animals showed clinical signs of urolithiasis and post mortem only a trace of calculous material was recovered from one lamb fed diet A. In the second experiment housed Suffolk and Suffolk cross lambs were fed a starter beginning at three to four weeks old and changed to a finisher at a liveweight of 23 kg. The feeds were either high magnesium starter (5.7) and finisher (6.0) or low magnesium starter (2.3) and finisher (2.8 g/kg DM). Twenty-two single lambs and 32 twins were assigned to both high and low magnesium diets. Lambs fed additional magnesium drank more water/kg DM intake and one of the single lambs showed clinical signs of urolithiasis and was killed. No others showed clinical signs and from the 62 killed there was no post mortem recovery of calculous material.     

Assessing dairy potential of western white-faced ewes

Two experiments were conducted to examine the milk producing ability of Western White-Faced sheep and to identify traits that correlate well with milk production. In Exp. 1, 31 Targhee ewes were milked and five samples were taken during 107-d lactations in which the ewes nursed twin lambs. Milk yield and composition, lamb weights, ewe weights, wool growth, and udder size also were measured. In Exp. 2, 24 ewes (Rambouillet x Finn-Dorset) were separated from their lambs at 7 wk and milked twice per day for eight more weeks, during which milk yield and composition, feed consumption, udder width, and ewe weights were measured. Results from Exp. 1 showed that lamb 30-d weights, ewe weights at breeding time, and udder width at peak lactation were highly correlated with suckled milk yield (r = .81, .75 and .66, respectively). Results from Exp. 2 indicated that lamb weights and ewe weights were not useful for predicting milk yield in dairy ewes, but feed intake and udder width were (r = .74 and .86, respectively). Single-day milk yield measurements were excellent estimators of total lactation yield in both experiments. Milk yields averaged 1,714 g/d in the suckled ewes and 477 g/d in the dairy ewes.     

Buffel grass (Cenchrus ciliaria L.) substitution for orange pulp on intake, digestibility, and performance of hairsheep lambs

Twenty Dorper x Pelibuey male lambs were used to evaluate the effect of substitution of forage with fresh orange pulp (FOP) in diets for fattening lambs on productive behavior, nutrient intake, apparent digestibility coefficient, and feeding costs. Lambs were divided into five groups (n?=?4) and then housed in individual pens during 70 d. Treatments consisted of five levels of FOP (0, 25, 50, 75 and 100%) which substituted buffel grass hay on the base diet (40:60%, forage:concentrate). Additionally, changes in chemical composition of FOP stored in stack during 8 d were evaluated (from the day 1 until day 8). Daily feed intake expressed as kg/day and % live weight, lamb growth rate, feeding cost of each lamb per day and per fattening period, hemicellulose intake, and DM, OM, CP, NDF and hemicellulose digestibility showed a quadratic effect (P?<?0.05), while DM, OM and CP intake presented a cubic effect (P?<?0.05) with the increasing level of FOP. The maximum estimated value for those variables was observed at 75% of hay replacement with FOP. With respect to changes in chemical composition of pulp stored, DM content increased (P?=?0.0011) from 210 to 310 g/kg FOP and OM, fiber fraction, and ash content were constant (P?>?0.05) among storage days. Therefore, replacing around 75% of buffel grass hay with FOP in diets for fattening lambs resulted in the best growth rate and more efficient diet utilization. Fresh orange pulp stored in a stack did not change its chemical composition, and did not affect its utilization as a sheep feedstuff.     

Effect of group size and feeder type on growth performance and feeding patterns in finishing pigs

The effects of four group sizes (2, 4, 8, and 12 pigs per pen) and two single-space feeder types (conventional and electronic feed intake recording equipment [FIRE]) on feed intake, growth performance, and feeding patterns were determined in 208 crossbred finishing pigs (equal numbers of barrows and gilts) between 84.4 (SD = 0.81) to 112.8 (SD = 1.08) kg BW over a 4-wk period. Pigs were given ad libitum access to a corn-soybean meal-based diet (15.9% CP; 0.79% lysine; 3,328 kcal ME/kg). The floor space allowance was 0.9 m2/pig for all treatments. Growth rates were not different for the two feeder types; however, feed intake was lower and gain:feed ratio higher for pigs on the FIRE feeders (P < 0.01). Feed intake, growth rate, and gain:feed ratio were not different (P > 0.05) among the group sizes. Number of feeder visits per day decreased and feed intake per visit, feeder occupation time per visit, feed consumption rate, and percentage of time the feeder was occupied increased with group size (P < 0.05). Feed intake per visit had the strongest correlation with daily feed intake (r = 0.54; P < 0.01) and was negatively correlated with gain:feed ratio (r = -0.38; P < 0.01). However, the correlations between growth performance and other feeding pattern traits were relatively weak (r < or = 0.30). As group size increased, diurnal variation in number of feeder visits and feed consumed per hour decreased. There was no difference in time spent sitting and standing between the two feeder types. The proportion of time spent eating was generally lower for the larger groups on both feeders. The proportion of time spent lying was similar across group sizes for pigs on the conventional feeders but was greater for pigs in the larger groups on the FIRE feeders. This study suggests that finishing pigs can maintain feed intake and growth rate by changing feeding behavior as group size increases from 2 to 12.     

Effects of diet and Aspergillus oryzae extract or Saccharomyces cervisiae on growth and carcass characteristics of lambs and steers fed to meet requirements of natural markets

Two studies were conducted to determine the effects of diet and feed additive on growth and carcass characteristics of lambs and cattle destined for all natural markets. In Exp. 1, 48 Dorset × Hampshire lambs (initial BW 29.4 ± 0.1 kg) were used in a randomized complete block experiment to determine the effects of Aspergillus oryzae extract, Amaferm (AMF) supplementation (1 g/d) in an 85% concentrate diet on growth and carcass characteristics. Lambs were allotted to 12 pens (4 lambs per pen), and blocked by sex and BW. Lambs were fed until the average BW of each pen reached a target BW (55.4 kg for wethers and 50.0 kg for ewes), at which time the entire pen of lambs was slaughtered. Amaferm resulted in a greater (P=0.07) G:F. In Exp. 2, 168 crossbred steers (initial BW 300 ± 0.7 kg) were used in a trial with a 3 × 2 factorial arrangement of treatments to examine the effects of 0.5 g/d of Saccaromyces cervisiae boulardii CNCM 1079-Levucell SB (LEV), or 3 g/d of AMF with 2 corn sources, dry whole-shelled corn or high moisture corn, on growth and carcass characteristics. Neither LEV nor AMF improved (P>0.10) carcass characteristics compared with control or non-feed-supplemented steers. Addition of LEV to high-concentrate, corn-based diets did not improve (P>0.10) growth performance of feedlot steers. However, addition of AMF to a diet composed of dry whole-shelled corn resulted in an improvement (P<0.05) in G:F (0.208 vs. 0.194). Results indicate that at the amounts fed, AMF may improve G:F for lambs and steers fed dry corn-based finishing diets.     

Behavior of ewes and lambs subjected to restraint fostering

The objective of this study was to investigate the development of maternal-filial social attachments between ewes and alien lambs using the technique of "restraint fostering." Forty-eight to 72 h after parturition, 22 Targhee -type ewes were separated from their natural lambs, placed in restraining devices ( stanchions ) and each exposed to a single alien lamb. After a period of 1 or 4 d of restraint, the ewes were subjected to five 10-min lamb acceptance tests over a 48-h period. The observer recorded butts and butt attempts by the ewe and successful and unsuccessful suckle attempts by the lamb. The ewe-lamb pairs were then housed in pens with other groups of ewes and lambs and observed intermittently for acceptance behaviors. Six of the 14 ewes restrained for 4 d and none of the eight ewes restrained for 24 h met the criterion for successful adoption within 48 h. After being housed in group pens, adoptions were achieved by three ewes in the 1-d group and an additional four ewes in the group restrained for 4 d. Ewes restrained for 24 h were significantly more aggressive toward fostered young than ewes restrained for 4 d. In addition, the proportion of successful suckling attempts was significantly lower for lambs fostered on ewes in the 1-d group. Both groups showed a decline in butts and butt attempts over successive acceptance tests, but while the proportion of successful suckling attempts declined for lambs housed with 1-d ewes, they increased over time for lambs fostered on ewes restrained for 4 d.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fattening performance and carcass traits of Chios male lambs fed under traditional and intensive feeding conditions

This study was carried out to compare the fattening performance and carcass traits of Chios male lambs fed under traditional and intensive feeding conditions. In the study, a total of 34 lambs were randomly separated into traditional (T) and intensive (I) groups in equal numbers. Lambs in group T were fed on ration prepared in local style and grazed in olive grove for 8 h/day. On the other hand, lambs in group I were fed on 255 g alfalfa hay animal⁻¹ day⁻¹ and ad libitum mixed feed. After a period of 8 weeks, lambs were transported to the slaughterhouse. The results showed that Chios lambs fed under intensive conditions has better performance and produced heavier carcass compared to those fed under traditional conditions. However, consumption of concentrate feed mixture was about twice as much in group I as in group T. Total feed consumption and feed conversion ratio was similar in each group. The values of carcass traits of lambs in group I were found to be significantly higher than those of group T. On the other hand, carcass fat thickness was slightly lower in group T. Traditional condition is considered to respond to better to consumer demands for lean lamb carcass.     

Haematology, blood biochemistry and tissue histopathology of lambs maintained on diets containing an insect controlling protein (Cry1Ac) in Bt-cottonseed

This experiment assessed the effect of feeding genetically modified cottonseed (Bt) containing an insect controlling protein (Cry1Ac) on haematology, blood biochemistry and histopathology of lambs. Haemato-biochemicals were estimated at periodic intervals, and histopathology at termination of experiment. Thirty three weaner lambs were fed a composite feed mixture (CFM) ad libitum individually, in three groups for 123 days. The isonitrogenous CFM had roughage (Perl Millet Stover) and concentrate ratio of 350:650. Diet fed to control lambs contained groundnut oil meal as protein source while other two groups received diet containing either whole cottonseed (N-Bt) or Bt-cottonseed (Bt-CS). Daily feed intake and average daily gain were similar among lambs of three groups. Lambs fed N-Bt diet had higher (p < 0.05) serum protein and globulin compared to control and Bt diets, while albumin content was higher (p = 0.018) in Bt diet fed lambs. Serum urea and creatinin content, alkaline phosphatase (ALP) and serum glutamate pyruvic transaminase (SGPT) activities were not different among lamb groups, while urea and creatinin content and ALP activities increased linearly (p < 0.001) with increased feeding period. Blood haemoglobin (Hb), haematocrit (Hc), white blood cells (WBC), mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC) ranged from 11.1% to 11.2%, 31.8% to 32.8%, 7.0 to 8.3 (× 10(3) /μl), 19.1 to 22.5 fl and 33.2% to 35.5%, respectively, were similar among lamb groups. Erythrocyte sedimentation rate (ESR) (p = 0.008) and red blood cell counts (p = 0.006) were higher in Bt diet fed lambs. Control and N-Bt diet fed lambs had mild fatty infiltration in liver and/or micro-calculi in renal cortex, and such lesions were not seen in Bt diet fed lambs. Growth, haemato-biochemical and histopathology did not change by Bt-CS feeding in growing lamb. However, before recommending the use of Bt-CS in routine feed formulations prolonged feeding experiments of Bt-cotton seed require.     

Effect of diets containing n-3 fatty acids on muscle long-chain n-3 fatty acid content in lambs fed low- and medium-quality roughage diets

In two experiments, each with 32 cross-bred ([Merino x Border Leicester] x Poll Dorset) wether lambs (26 to 33 kg weight range), animals were randomly assigned to one of four treatments. A mixture of lucerne chaff:oaten chaff was used as a basal diet, offered in different ratios. Animals were allowed to consume on a free-access basis in Exp. 1 or 90% of ad libitum intake in Exp. 2 in order to provide a low- (6.5 MJ ME/d) and medium- (9.5 MJ ME/d) quality basal diet, respectively. Isoenergetic amounts of lipid supplements, fish meal (80 g DM), canola meal (84 g DM), and soy meal (75 g DM) were tested in Exp. 1. In Exp. 2, fish meal (9% DM), unprotected rapeseed (7% DM), and protected canola seed (6% DM) were fed as supplements. At the end of 53-d (Exp. 1) or 46-d (Exp. 2) experimental periods, lambs were slaughtered at a commercial abattoir and at 24 h postmortem longissimus thoracis (LT) muscle was collected for the analysis of fatty acid (FA) composition of structural phospholipid and storage triglyceride fractions. Fish meal diet increased LT muscle long-chain n-3 FA content by 27% (P < 0.02) in Exp. 1 and 30% (P < 0.001) in Exp. 2 compared with lambs fed the basal diet, but fish meal decreased (P < 0.01) the n-6 FA content only in Exp. 1. Soy meal and protected canola seed diets increased (P < 0.01) LT muscle n-6 FA content but did not affect long-chain n-3 FA content. Longissimus thoracis muscle long-chain n-3 FA were mainly deposited in structural phospholipid, rather than in storage triglyceride. In both Exp. 1 and Exp. 2, the ratio of n-6:n-3 FA in LT muscle was lowest (P < 0.01) in lambs fed fish meal supplement compared with all other treatments. Protected canola seed diet increased the ratio of n-6:n-3 FA (P < 0.01) and PUFA:saturated fatty acid (P < 0.03) content from those animals fed the basal, fish meal, and unprotected rapeseed diets in Exp. 2. This was due to an increase in muscle n-6 FA content, mainly linoleic acid, of both phospholipid (P < 0.001) and triglyceride (P < 0.01) fractions and not to an increase in muscle n-3 FA content. The results indicate that by feeding fish meal supplement, the essential n-3 FA can be increased while lowering the ratio of n-6:n-3 content in lamb meat to an extent that could affect nutritional value, attractiveness, and the economic value of meat.     

Effects of supplemental safflower and vitamin E during late gestation on lamb growth, serum metabolites, and thermogenesis

Twin-bearing Targhee ewes (Exp. 1, 1 yr, n = 42) and 1,182 single- and twin-bearing whiteface range ewes (Exp. 2, n = 8 experimental units over 2 yr) were used in a 2 x 2 factorial arrangement of treatments to determine the effect of supplemental energy source and level of vitamin E supplement on lamb serum metabolites and thermogenesis (Exp. 1) and on lamb growth (Exp. 2). During late gestation, ewes were individually fed (Exp. 1) or group-fed (Exp. 2) a daily supplement. Supplements were 226 g/ewe of daily safflower seed (DM basis; SS) with either 350 IU/ewe daily (VE) or no added supplemental (VC) vitamin E; or 340 g/ewe daily of a barley-based grain supplement (DM basis; GC) and either VE or VC. One hour postpartum in Exp. 1, twin-born lambs were placed in a 0 degrees C dry cold chamber for 30 min. Lamb rectal temperature was recorded every 60 s and blood samples were taken immediately before and after cold exposure. In Exp. 2, lambs were weighed at birth, at turnout from confinement to spring range (32 d of age +/- 7; turnout), and at weaning (120 d of age +/- 7). Ewes were weighed at turnout and weaning. In Exp. 1, a level of vitamin E x energy source interaction was detected (P < 0.10) for body temperature and change in NEFA and glucose concentrations. Lambs from SSVC ewes had the lowest (P = 0.01) body temperature and had decreased (P = 0.08) NEFA concentration. The SS lambs tended to have decreased (P < 0.11) concentrations of blood urea N (BUN) and thyroxine at 0 min than did lambs born to GC ewes. After 30 min of cold exposure, SS lambs had increased and GC lambs had decreased BUN, triiodothyronine, and triiodothyronine:thyroxine concentrations (P < 0.10). In Exp. 2, kilograms of lamb per ewe at turnout and weaning and lamb survival at weaning were greater (P < 0.07) for GC than SS lambs. Based on the decreased body temperature in SSVC lambs at birth, the greater change in BUN during the cold exposure for SS than GC lambs, and the decreased survival rate for SS than GC lambs, SSVC-supplemented ewes appeared to give birth to lambs with an apparently decreased energetic capacity. This may compromise the ability of the newborn lamb to adapt to extreme environmental conditions.     

Comparison of the effects of three methods of harvesting and storing alfalfa on nutrient digestibility by lambs and feedlot performance of steers

Two lamb digestion and three steer growth experiments were conducted to study the feeding value of alfalfa harvested as direct-cut silage (DCS) with grain added prior to ensiling or as low-moisture silage (LMS) or hay with grain added at feeding. In all experiments, alfalfa-grain mixtures contained approximately 50% alfalfa and 50% concentrate (dry matter [DM] basis). In Exp. 1, lambs fed DCS alone consumed less DM than lambs fed LMS or hay alone or any of the alfalfa-grain mixtures. Apparent digestibilities of DM and fiber components were higher (P less than .05) for DCS than for LMS or hay. Lambs that were fed LMS digested more (P less than .05) DM and fiber components than lambs fed hay. Addition of grain resulted in increased (P less than .05) DM digestibility and decreased (P less than .05) digestibilities of neutral detergent fiber and acid detergent fiber. In Exp. 2, growing steers (271 kg) fed DCS-grain had increased (P less than .05) weight gains compared with steers fed hay-grain. Steers fed any of the alfalfa-grain mixtures gained weight more rapidly (P less than .05) than steers fed corn silage (CS)-based diets. In a third experiment, finishing steers (283 kg) fed DCS-grain, LMS-grain, hay-grain or CS-based diets performed similarly (P greater than .05), although steers fed DCS-grain had higher (P less than .05) dressing percentages and yield grades than steers that were fed the other three diets and were fatter (P less than .05) than those fed LMS-grain or CS. In Exp. 4, lambs fed DCS-grain or LMS-grain had higher (P less than .05) apparent DM and organic matter digestibilities than lambs fed CS-based diets with similar forage:grain proportions. In Exp. 5, finishing steers (326 kg) fed DCS-grain gained similarly (P greater than .05) to steers fed LMS-grain or an 85% concentrate diet based on high-moisture corn. Steers fed CS diets had lower (P less than .05) gains and increased (P less than .05) feed per gain compared with steers fed DCS-grain, LMS-grain or high-moisture corn.     

Effects of restricted feed intake on finishing pigs weighing between 68 and 114 kilograms fed twice or 6 times daily

In a previous study with limit-fed gestating gilts, we observed that gilts fed 6 times/d had greater ADG than those fed the same amount over 2 feedings. To confirm these earlier responses, we used finishing pigs as a model in two 42-d trials and two 28-d trials to evaluate the effects of restricted feed intake and feeding frequency (2 vs. 6 times/d, floor fed) on pig performance between 68 and 114 kg. In all experiments, pigs (10/pen) were housed in 1.8 × 3.1 m pens with a half-solid, half-slatted concrete floor. Pigs were fed a corn- and soybean meal-based diet formulated to 1.15% standardized ileal digestible Lys and 3,294 kcal of ME/kg. In Exp. 1 to 3, energy and Lys were supplied to pigs according to NRC (1998) calculations to target an ADG of 0.80 kg. In Exp. 4, the diet was supplied to pigs to target an ADG of 0.80 kg (low feed intake) or 0.95 kg (high feed intake) to determine if the amount of energy above the maintenance requirement and feeding frequency affected pig performance. Pigs were fed by dropping similar amounts of feed onto the solid concrete floor either 2 (0700 or 1400 h) or 6 times (3 meals within 2 h at the morning and afternoon feedings) per day with an Accu-Drop Feed Dispenser (AP Systems, Assumption, IL). In Exp. 1 and 2, pigs fed 6 times daily had increased (P < 0.02) ADG and G:F compared with pigs fed 2 times per day. Greater feeding frequency increased (P < 0.05) the duration of time spent feeding and standing and reduced the lying time. In Exp. 3, a third treatment was included to determine whether the improvements in performance were due to decreased feed wastage. This treatment was designed to minimize feed wastage by dropping feed closer to the floor for pigs fed 2 times per day. Pigs fed 6 times daily had improved (P < 0.05) ADG and G:F compared with pigs in either treatment fed 2 times per day. No difference (P > 0.05) in performance was observed between pigs fed 2 times per day when feed was dropped from the feed drop or by the modified method. In Exp. 4, increasing the feeding frequency from 2 to 6 times per day improved (P < 0.01) ADG and G:F for pigs fed the low feed intake and tended to increase (P < 0.06) ADG and improved (P < 0.05) G:F for pigs fed the high feed intake. In limit-feeding situations, increasing the frequency of feeding from 2 to 6 times per day improved pig performance, which confirmed our earlier findings in gestating gilts.     

Thermogenesis, blood metabolites and hormones, and growth of lambs born to ewes supplemented with algae-derived docosahexaenoic acid

Neonatal lamb mortality is a major factor affecting profitability in the sheep industry, and lamb thermogenesis is a key element in neonatal lamb survival. Increased lamb vigor has been reported when ewes were supplemented during late gestation with algae-derived docosahexaenoic acid (DHA); however, the effects of DHA on lamb thermogenesis and immunocompetence have not been investigated. Eighty twin-bearing Targhee ewes (ages 2 to 5 yr; 68.5 ± 3 kg) were assigned randomly to 1 of 2 supplement treatments to determine the effects of feeding DHA to ewes during late gestation and early lactation on lamb thermogenesis, serum metabolites and hormones, and lamb growth. Supplement treatments were 12 g·ewe(-1)·d(-1) of algae-derived DHA (DHA Gold Advanced Bionutrition Corp., Columbia, MD; algae-derived DHA); and no algae-derived DHA (control). Supplements were individually fed daily during the last 30 d (±7 d) of gestation and pen fed (6 pens/treatment with 6 or 7 ewes/pen) during the first 38 d (±7 d) of lactation. One hour after lambing and before nursing, twin-born lambs were weighed, blood sampled via jugular puncture, and placed in a dry cold chamber for 30 min (0°C), and rectal temperatures were recorded every minute for 30 min. Lambs were removed from the cold chamber, blood sampled, warmed for 15 min, and returned to their dam. Ewes were blood sampled, and colostrum samples were collected 1 h postpartum. Ewe and lamb sera were assayed for glucose, NEFA, cortisol, and leptin. Lamb rectal temperature, glucose, NEFA, cortisol, leptin, and birth weights did not differ between treatments. The BW at 38 d was greater (P = 0.03) for lambs born to control ewes than for lambs born to algae-derived DHA-supplemented ewes; however, the colostrum of algae-derived DHA-supplemented ewes had a greater specific gravity (P = 0.05) than for control ewes. Overall, despite a potentially positive effect on ewe colostral IgG concentrations, supplementation of algae-derived DHA during late gestation and early lactation had a negative effect on lamb BW and did not affect indices of lamb thermogenesis.     

Dietary concentrate level affects the feed sorting behaviour of lambs

The objective of this study was to evaluate the effect of forage concentration on sorting, nutrient intake and feeding behaviour of growing lambs. Twelve weaned lambs were exposed, in a crossover design with 7‐day periods, to each of two treatment diets: (i) lower‐concentrate diet (LC; 40.0% concentrate) and (ii) a higher‐concentrate diet (HC; 60.0% concentrate). Alfalfa hay was used as forage source. Sorting was determined by subjecting fresh feed and ort samples to particle separation and expressing the actual intake of each particle fraction as a percentage of the predicted intake of that fraction. Lambs sorted against long particles (>19 mm) on both treatments. On the LC diet, lambs sorted for medium particles, whereas animals fed the HC diet did not sort for or against medium particles. Lambs sorted for fine particles (<1.18 mm) on both treatments (p < .05). The extent of sorting for the fine particles was greater on the LC diet compared with the HC diet (p < .05). Dry matter intake was increased by increasing the concentrate content of the diet. Intake per visit and eating rate increased, and total chewing time was decreased in lambs fed HC diet. In conclusion, lambs sorted most against the longest particles and for the fine particles. Furthermore, feed sorting behaviour is affected by the forage level, and lambs sorted more for the fine particles in the LC diet.